1. Field of the Invention
This invention relates generally to a charge injection imaging device with low noise readout and, more particularly, to a charge injection imaging device which can provide image defining signals for each succeeding photosensitive element thereof from which noise defining signals are automatically offset.
2. Description of the Prior Art
Charge injection imaging devices comprising a plurality of photosensitive elements arranged in a matrix of rows and columns are well known in the art. Each of the photosensitive elements comprises a row and column electrode. All the row electrodes in each row are in common connection with respect to each other, and all the column electrodes in each column are in common connection with respect to each other also. Incident scene light operates to photogenerate minority charge carriers in potential wells under each pair of electrodes in each photosensitive element. The photogenerated charges may be transferred between wells within each of the photosensitive elements by applying appropriate bias voltages to respective ones of the column and row electrodes. In one well-known mode of operation, the charges may be sensed from the electrodes out of the CID along common lines interconnecting each column of electrodes.
Most recently, it has been suggested that amplifiers may be integrated with the column electrodes. Such amplifiers preferably should be of low bandwidth in order to facilitate low noise performance when reading out the charge injection imaging device. Each amplifier must also be of substantially narrow width or pitch in order to accommodate its alignment with a respective one of the columns without substantially increasing the width of the silicon area of the charge injection imaging device.
Not only must the amplifiers be of the aforementioned narrow pitch while still exhibiting low noise and bandwidth performance characteristics, but noise inherent to the charges sensed from the photosensitive elements such as KTC noise and fixed pattern noise must also be offset from the output signal. KTC noise is inherently induced in each of the common column electrode interconnect lines upon resetting the electrode voltages while fixed pattern noise occurs due to variations in the crossing of the common column electrode interconnect lines with the common row electrode interconnect lines as a result of inherent limitations in processing.
Therefore, it is a primary object of this invention to provide a charge injection imaging device in which image data is read out in a manner by which KTC noise and fixed pattern noise are automatically cancelled.
It is a further object of this invention to provide a charge injection imaging device in which low bandwidth amplifiers are confined within the narrow pitch between columns.
Other objects of the invention will be in part obvious and will in part appear hereinafter. The invention accordingly comprises a system possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure.